Image sensor, imaging apparatus, and imaging method

ABSTRACT

There is provided an image sensor including a normal pixel group composed of a plurality of normal pixels, each of the normal pixels having a photoelectric conversion device for photoelectrically converting an incident light, and a detection pixel configured to detect a light incident from a neighboring pixel by the photoelectric conversion device within an effective pixel area of the normal pixel group.

BACKGROUND

The present disclosure relates to image sensors, imaging apparatus, andimaging methods. More particularly, the present disclosure relates to animage sensor, imaging apparatus and imaging method capable of moreaccurately correcting color mixing.

In the related art, there has been proposed a method of pre-setting acolor mixing correction coefficient and correcting color mixing by usingthe color mixing correction coefficient (see, e.g., Japanese PatentLaid-open No. 2010-16419).

There has been also proposed a method of providing a color mixingdetection pixel at an optical black area (OPB area) outside an effectivepixel as a method of dynamically correcting color mixing (see, e.g.,Japanese Patent Laid-open No. 2010-239192).

Further, there has been also proposed a method of providing an OPBwithin an effective pixel (see, e.g., Japanese Patent Laid-open No.2010-147785).

SUMMARY

However, in the method of pre-setting the color mixing correctioncoefficient value which is described in Japanese Patent Laid-open No.2010-16419, the manufacturing variations (for example, film thickness ofcolor filter, or positional aberration of on-chip lens) have not beencontemplated. Since color mixing ratio is changed depending on a lightwavelength as well as a light source or a subject to be picked up, themethod of pre-setting the color mixing correction coefficient has notcontemplated on such cases.

Further, in the method described in Japanese Patent Laid-open No.2010-239192, if a color mixing detecting pixel is provided at an areaoutside of the effective pixel, then the angle of incidence within theeffective pixel is different from the angle of incidence outside of theeffective pixel because the amount of color mixing is a value which ischanged depending on the angle of light incidence. Accordingly, it isnot possible to obtain the accurate amount of color mixing.

Moreover, in the method described in Japanese Patent Laid-open No.2010-147785, the color mixing caused within Si has been notcontemplated. If an OPB is provided only at a pixel of particular color,then, as well as black level, a color mixing being entered into thepixel is outputted. If the value is subtracted from other color pixel,then there is a possibility that the obtained color mixing ratio will beinaccurate because the color mixing is varied depending on colors. Inaddition, since the amount of color mixing is varied depending on imageheight (position within image sensor), it is necessary to perform anoperation considering the optical distance. However, the methoddescribed in Japanese Patent Laid-open No. 2010-147785 has not mentionedabout it.

In view of the foregoing, it is desirable to provide a technologycapable of more accurately correcting color mixing.

According to an embodiment of the present disclosure, there is providedan image sensor which includes a normal pixel group composed of aplurality of normal pixels in which each of the normal pixels has aphotoelectric conversion device for photoelectrically converting anincident light, and a detection pixel configured to detect a lightincident from a neighboring pixel by the photoelectric conversion devicewithin an effective pixel area of the normal pixel group.

The detection pixel may further include a light shielding filmconfigured to shield an incident light incident upon the detection pixelfrom outside.

The light shielding film may be formed by a wiring layer.

The light shielding film may formed by a plurality of wiring layers.

Each of the wiring layers may have a gap formed thereon at differentpositions from each other.

Each of the wiring layers may be arranged depending on an incident angleof an incident light.

The light shielding film may be formed by a metal disposed on thephotoelectric conversion device.

The image sensor may include a plurality of the detection pixels.

The image sensor may further include a filter configured to transmit anincident light of a predetermined wavelength. A result obtained bydetecting a light incident from the neighboring pixel by the detectionpixel may be used to correct a pixel value of a normal pixel providedwith a filter configured to transmit an incident light having the samewavelength as a filter provided at the detection pixel.

The detection pixels may be provided in positions that are notcontiguous with each other.

According to another embodiment of the present disclosure, there isprovided an imaging apparatus which includes an image sensor and asubtraction unit. the image sensor includes a normal pixel groupcomposed of a plurality of normal pixels in which each of the normalpixels has a photoelectric conversion device for photoelectricallyconverting an incident light, and a detection pixel configured to detecta light incident from a neighboring pixel by the photoelectricconversion device within an effective pixel area of the normal pixelgroup. The subtraction unit is configured to subtract a light amount ofa light incident from a neighboring pixel of the normal pixel from apixel value of the normal pixel by using a light amount of a lightdetected by the detection pixel of the image sensor.

The subtraction unit may include a selection unit configured to select adetection pixel to be used in subtracting the light amount, a lightamount calculation unit configured to calculate the light amountincluded in a pixel value of a normal pixel to be processed using apixel value of the detection pixel selected by the selection unit, and alight amount subtraction unit configured to subtract the light amountcalculated by the light amount calculation unit from a pixel value of anormal pixel to be processed.

The selection unit may select a plurality of detection pixels. The lightamount calculation unit may calculate the light amount by adding aweight to each pixel value of the plurality of detection pixelsdepending on a positional relationship between the plurality ofdetection pixels selected by the selection unit and a normal pixel to beprocessed.

The light amount calculation unit may change the detection pixel used tocalculate the light amount to another detection pixel or prohibit thedetection pixel from being used, when a pixel value of a neighboringpixel of the detection pixel selected by the selection unit issaturated.

The light amount calculation unit may change the detection pixel used tocalculate the light amount to another detection pixel or prohibit thedetection pixel from being used, when the detection pixel selected bythe selection unit is a defective pixel.

The light amount calculation unit may further correct the calculatedlight amount to reduce the light amount, when a normal pixel to beprocessed is adjacent to a detection pixel.

The subtraction unit may subtract a black level as well as the lightamount from the pixel value of the normal pixel.

The subtraction unit may include a selection unit configured to select adetection pixel to be used in subtracting the light amount, a ratiocalculation unit configured to calculate a ratio of the light amountincluded in a pixel value of a normal pixel to be processed using apixel value of the detection pixel selected by the selection unit, and amultiplication unit configured to multiply a pixel value of a normalpixel to be processed by a ratio of an incident light inputted to thenormal pixel to be processed from outside, the ratio of the incidentlight is corresponded to the ratio of the light amount calculated by theratio calculation unit.

The normal pixel and the detection pixel of the image sensor may have avertical spectral structure.

According to another embodiment of the present disclosure, there isprovided an imaging method of an imaging apparatus having an imagesensor. The image sensor includes a normal pixel group composed of aplurality of normal pixels in which each of the normal pixels has aphotoelectric conversion device for photoelectrically converting anincident light, and a detection pixel configured to detect a lightincident from a neighboring pixel by the photoelectric conversion devicewithin an effective pixel area of the normal pixel group. The imagingmethod includes subtracting, at a subtraction unit, a light amount of alight incident from a neighboring pixel of the normal pixel from a pixelvalue of the normal pixel using a light amount of a light detected bythe detection pixel of the image sensor.

In accordance with an embodiment of the present disclosure, there is aprovided a configuration which includes a normal pixel group composed ofa plurality of normal pixels and a detection pixel. Each of the normalpixels has a photoelectric conversion device for photoelectricallyconverting an incident light. The detection pixel is configured todetect a light incident from a neighboring pixel by the photoelectricconversion device within an effective pixel area of the normal pixelgroup.

In accordance with another embodiment of the present disclosure, a lightamount of a light incident from a neighboring pixel of the normal pixelis subtracted from a pixel value of the normal pixel using a lightamount of a light detected by the detection pixel of the image sensor.

According to the embodiments of the present disclosure described above,it is possible to correct color mixing caused in an image device.Especially, the color mixing can be more accurately corrected withoutdepending on imaging circumstances such as an angle of light incidence,a color temperature, a subject to be picked up, and so on.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram illustrating a configuration of animage device according to an embodiment of the present disclosure;

FIG. 2 is a diagram illustrating an example of how color mixing iscaused;

FIG. 3 is a diagram illustrating an example of a color mixing detectionpixel;

FIG. 4 is a diagram illustrating an example of a light shielding film;

FIG. 5 is a diagram illustrating an example of a light shielding film;

FIG. 6 is a diagram illustrating an example of a light shielding film;

FIG. 7 is a diagram illustrating an example of a Bayer array;

FIG. 8 is a diagram illustrating an arrangement example of a colormixing detection pixel;

FIG. 9 is a diagram illustrating an arrangement example of a colormixing detection pixel;

FIG. 10 is a diagram illustrating an undesirable arrangement example ofa color mixing detection pixel;

FIG. 11 is a diagram illustrating another arrangement example of thecolor mixing detection pixel;

FIG. 12 is a diagram illustrating an example of how the amount of colormixing is subtracted;

FIG. 13 is a diagram illustrating a configuration example of a colormixing subtraction unit;

FIG. 14 is a diagram illustrating an example of calculating the amountof color mixing;

FIG. 15 is a diagram illustrating an example of calculating the amountof color mixing;

FIG. 16 is a diagram illustrating an example of calculating the amountof color mixing;

FIG. 17 is a diagram illustrating an example of calculating the amountof color mixing;

FIG. 18 is a diagram illustrating an example of how the amount of colormixing is subtracted;

FIG. 19 is a diagram illustrating an example of how defect is corrected;

FIG. 20 is a flowchart illustrating a procedure example of an imagingprocess;

FIG. 21 is a flowchart illustrating a procedure example of a colormixing subtraction process;

FIG. 22 is a diagram illustrating another configuration example of theimaging apparatus;

FIG. 23 is a diagram illustrating another example of how the amount ofcolor mixing is subtracted;

FIG. 24 is a diagram illustrating an example of how a dark current isshading;

FIG. 25 is a flowchart illustrating another procedure example of theimaging process;

FIG. 26 is a flowchart illustrating a procedure example of a colormixing and black level subtraction process;

FIG. 27 is a diagram illustrating another configuration example of thecolor mixing subtraction unit;

FIG. 28 is a diagram illustrating another operation example of colormixing amount subtraction;

FIG. 29 is a flowchart illustrating a procedure example of a colormixing subtraction process;

FIG. 30 is a diagram illustrating an example of when light amount issaturated;

FIG. 31 is a diagram illustrating another example of color mixingsubtraction when light amount is saturated;

FIG. 32 is a flowchart illustrating a procedure example of a colormixing detection pixel specifying process;

FIG. 33 is a diagram illustrating a color mixing correction process ofneighboring pixels of a color mixing detection pixel;

FIG. 34 is a flowchart illustrating a procedure example of a colormixing subtraction process;

FIG. 35 is a block diagram illustrating yet another configurationexample of the imaging apparatus;

FIG. 36 is a block diagram illustrating an example of a verticalspectral structure;

FIG. 37 is a diagram illustrating an arrangement example of a colormixing detection pixel of a vertical spectral structure;

FIG. 38 is a diagram illustrating an example of a color mixing detectionpixel of a vertical spectral structure;

FIG. 39 is a flowchart illustrating yet another example of the imagingprocess;

FIG. 40 is a block diagram illustrating yet another configurationexample of the imaging apparatus;

FIG. 41 is a flowchart illustrating still another example of the imagingprocess;

FIG. 42 is a block diagram illustrating still another configurationexample of the imaging apparatus; and

FIG. 43 is a block diagram illustrating a configuration example of apersonal computer.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the appended drawings, structural elementsthat have substantially the same function and structure are denoted withthe same reference numerals, and repeated explanation of thesestructural elements is omitted.

Embodiments for implementing the present disclosure (hereinafter simplyreferred to as “embodiment”) will be described below. In addition, thedescription will be made in the following order.

1. First Embodiment (sequential correction of amount of color mixing andblack level)

2. Second Embodiment (simultaneous correction of amount of color mixingand black level)

3. Third Embodiment (application example)

4. Fourth Embodiment (vertical spectral structure: sequential correctionof amount of color mixing and black level)

5. Fifth Embodiment (vertical spectral structure: simultaneouscorrection of amount of color mixing and black level)

6. Sixth Embodiment (application example: imaging apparatus)

7. Seventh Embodiment (personal computer)

First Embodiment

[Configuration of Imaging Apparatus]

FIG. 1 is a diagram illustrating a configuration example of an imagingapparatus according to an embodiment of the present disclosure. As shownin FIG. 1, the imaging apparatus 100 captures a subject, converts animage of the subject into electrical signals, and outputs the electricalsignals.

As shown in FIG. 1, the imaging apparatus 100 includes a lens 101, adiaphragm 102, an image sensor with color filter 103, ananalog-to-digital (A/D) converter 104, a clamping unit 105, a colormixing subtraction unit 106, and a defect correction unit 107. Theimaging apparatus 100 also includes a demosaic unit 108, a linear matrixunit 109, a gamma correction unit 110, a luminance and chroma signalgeneration unit 111, and an interface (I/F) unit 112.

The lens 101 is configured to adjust a focal length of light incidentupon the image sensor with color filter 103. The diaphragm 102 isconfigured to adjust an amount of light incident upon the image sensorwith color filter 103. The lens 101 and the diaphragm 102 forms aprocessing unit of an optical system, and detailed configurationsthereof are not limited to any particular configuration. For example,the lens 101 may be configured to include a plurality of lenses.

As shown by the dotted arrow in FIG. 1, the incident light transmitsthrough both the lens 101 and the diaphragm 102 and irradiates the imagesensor with color filter 103.

The image sensor with color filter 103 includes a photoelectricconversion device for each pixel and converts incident light intoelectrical signal. The photoelectric conversion device may be aphotodiode. Specifically, the image sensor with color filter 103includes a normal pixel group having a plurality of normal pixels. Eachof the plurality of normal pixels includes a photoelectric conversiondevice for converting incident light into electrical signal. The imagesensor with color filter 103 may be a charge coupled device (CCD) imagesensor. In the CCD image sensor, the photoelectric conversion deviceperforms light transmission using a circuit device called CCD to readout electric charge generated from light. Also, the image sensor withcolor filter 103 may be a complementary metal oxide semiconductor (CMOS)image sensor having an amplifier for each unit cell by using a CMOS.

The image sensor with color filter 103 includes color filters at aposition of the photoelectric conversion device on which light isincident. In the color filters, each filter of red (R), green (G), andblue (B) colors are arranged on their respective photoelectricconversion devices, for example, in a Bayer array. Specifically, theimage sensor with color filter 103 converts a light incident upon eachcolor transmitted through respective filters into electrical signal andsupplies the electrical signal to the analog-to-digital (A/D) converter104.

The color filters of the image sensor with color filter 103 may haveoptional colors and also may have colors other than RGB. Some or all ofthe RGB colors may not be used. In addition, arrangement of each coloris also optional and other arrays than the Bayer array may be used. Forexample, a clear bit type pixel array, a dye-based color filter, a whitepixel (see, Japanese Patent Laid-open No. 2010-296276) and so on may beused for an arrangement of each color.

In the following, it is assumed that RGB color filters of the imagesensor with color filter 103 are arranged in the Bayer array.

The A/D converter 104 is configured to convert electrical signal (analogsignal) of RGB supplied from the image sensor with color filter 103 intodigital data (image data). The A/D converter 104 supplies the image data(RAW data) of the digital data to the clamping unit 105.

The clamping unit 105 is configured to subtract black level from theimage data. The black level is a level which is determined as blackcolor. The clamping unit 105 supplies the image data from which theblack level is subtracted to the color mixing subtraction unit 106.

The color mixing subtraction unit 106 is configured to subtract a colormixing component from the image data. The color mixing component is atype of light component transmitted through the filters of neighboringpixels. The color mixing subtraction unit 106 supplies the image datafrom which the color mixing component is subtracted to the defectcorrection unit 107.

The defect correction unit 107 is configured to correct a pixel value ofa defective pixel from which a proper pixel value is not obtained. Thedefect correction unit 107 supplies the image data in which thedefective pixel is corrected to the demosaic unit 108.

The demosaic unit 108 is configured to convert RAW data into RGB data byperforming a demosaic process on the RAW data and by compensating colorinformation. The demosaic unit 108 supplies the image data (RGB data) onwhich the demosaic process is performed to the linear matrix unit 109.

The linear matrix unit 109 is configured to correct each color signal ofimage data using a matrix coefficient and perform a process for changingthe color reproducibility so as to bridge the gap between a chromaticitypoint of primary colors (RGB) defined by specification and an actualchromaticity point of a camera. The linear matrix unit 109 supplies theimage data in which the process for changing the color reproducibilityis performed to the gamma correction unit 110.

The gamma correction unit 110 is configured to adjust the relativerelationship between a color of the image data and the characteristicsof an output device, and perform a gamma correction process forobtaining representations more close to the original. The gammacorrection unit 110 supplies the processed image data (RGB data) to theluminance and chroma signal generation unit 110.

The luminance and chroma signal generation unit 111 is configured togenerate a luminance signal (Y) and chrominance signals (Cr, Cb) fromthe RGB data supplied from the gamma correction unit 110. The luminanceand chroma signal generation unit 11 supplies the generated luminanceand chrominance signals (Y, Cr, Cb) to the interface (I/F) unit 112.

The interface (I/F) unit 112 outputs the image data (luminance/chromasignal) supplied from the luminance and chroma signal generation unit 11to the outside of the imaging apparatus 100 (for example, storage devicefor storing the image data or display device for displaying an image ofthe image data).

[Image Sensor with Color Filter]

Subsequently, each unit of the imaging apparatus will be described indetail. First, the image sensor with color filter 103 will be describedin detail below.

In an image sensor of the related art, as shown in FIG. 2, an opticalblack area (OPB) is provided at the outside of the effective pixel areaof the normal pixel group, and black level is detected in the OPB area.In each pixel within the effective pixel area, the incident light passedthrough an on-chip lens, a color filter, and a waveguide is irradiatedon a photodiode (Si photodiode). The photodiode converts incident lightinto electrical signal, accumulates electric charge, and then outputsthe electric charge at a predetermined timing.

As shown in FIG. 2, in accordance with the image sensor of the relatedart, there was a possibility that the incident light passed through theon-chip lens, the color filter and the waveguide of each pixel will beirradiated on any neighboring pixels besides the photodiode of thetarget pixel within a silicon photodiode. Furthermore, there also was apossibility that the incident light will be leaked into the neighboringpixels in the outside of the silicon photodiode such as the waveguideand so on.

As a result, there was a possibility that a part of incident lighttransmitted through the color filter of neighboring pixels adjacent tothe target pixel as well as incident light of the target pixel will beirradiated on the photodiode of a certain pixel (target pixel). In otherwords, there was a possibility that color mixing will be caused by lightincident upon the target pixel and also by light having a colordifferent from the light incident upon the target pixel.

Whereas, in the image sensor with color filter 103 according to theembodiment, as shown in FIG. 3, a color mixing detection pixel 121configured to detect the amount of color mixing is provided within aneffective pixel area of the normal pixel group. In the color mixingdetection pixel 121, a photodiode is covered with a light shielding film122. This substantially blocks any light originating from upper portionthan the Si photodiode from entering the Si photodiode. That is, in thecolor mixing detection pixel 121, the incident light componenttransmitted through the color filter of the target pixel is blocked bythe light shielding film 122, and only the incident light componenttransmitted through a color filter of any neighboring pixel is detectedby the photodiode.

As shown in FIG. 3, a plurality of the color mixing detection units 121are disposed within the effective pixel area. In the example of FIG. 3,thirty five color mixing detection units 121 (7 rows×5 columns=35) areprovided within the effective pixel area. In addition, the number of thecolor mixing detection unit 121 is not particularly limited and can besuitably selected. If the number of the color mixing detection unitincreases, then it is possible to more accurately calculate the amountof color mixing. However, since the color mixing detection pixel do nothave a normal signal value, the color mixing detection pixel iseventually regarded as a defective pixel and then is replaced with anormal pixel value. Therefore, the number of pixel which is regarded andprocessed as a defective pixel can be reduced by minimizing the numberof the color mixing detection pixel as small as possible. This allowsmalfunctions (for example, false color or resolution degradation) causedby defect correction to be prevented.

The position of the color mixing detection unit 121 within the effectivepixel area is not particularly limited. However, in order to accuratelyperform the color mixing correction by increasing the robustness againstthe bias of the amount of color mixing (pixel characteristics) withinthe effective pixel area, it is desirable to dispose the color mixingdetection unit 121 so that it may be distributed within the effectivepixel area as evenly as possible.

The light shielding film 122 may be made of any material as long as thematerial prevents the light transmitted through the color filter of thetarget pixel from entering the photodiode. For example, for a frontsurface illuminated sensor, as shown in FIG. 4A, the light shieldingfilm 122 may be a wiring layer made of a metal (for example, copper (CU)or aluminum (Al)). Also, for a back surface illuminated sensor, as shownin FIG. 4B, the light shielding film 122 may be made of a metal (forexample, tungsten (W)) formed on the photodiode. Of course, suitablemethods other than those described above may be used to form the lightshielding film 122.

For the formation pattern of the light shielding film, any techniquecapable of light-shielding may be used. For example, as shown in FIG.5A, the light shielding is achievable by using a plurality of wiringlayers (the plurality of wiring layers work as the light shielding film122). However, if the wiring layer is formed large enough to cover theentire pixel, then there is a possibility that the light shielding filmwill be peeled off during a process of forming the film (for example,dishing that arise when surface polishing (a chemical mechanicalpolishing (CMP))). Accordingly, there is a possibility that thethickness of each of the wiring layers becomes thinned, thus theincident light of the target pixel will be transmitted through thewiring layers without being blocked.

For example, as shown in FIG. 5C, it may be possible to provide aconfiguration that a gap is formed at respective parts of each wiringlayer and one wiring layer shields a light leaking from the gap formedin another wiring layer. As shown in FIG. 6, it also may be possible toprovide a configuration that the light shielding film has a minimum sizeand an optimal exit pupil correction is performed in correspondence withthe angle of incidence. For example, in the case of FIG. 6A, since theincident light entering the target pixel has the angle of incidence ofzero (0) degree, the light shielding film 122 (wiring layers) isdisposed in the proximity of the center of the pixel so as to preventthe incident light from entering the proximity of the center of thepixel. In the case of FIG. 6B, since a light is incident upon the targetpixel from an oblique direction, the on-chip lens, the color filter andthe wiring layer which is serving as the light shielding film 122 areeach disposed depending on the angle of light incidence.

This allows reducing a shielding area (area size of the wiring layerserving as the light shielding film 122) necessary to shield the pixelfrom entering of light. Thus, it is possible to prevent the lightshielding film from being peeled off during a process of forming thefilm (for example, dishing caused by CMP).

As shown in FIG. 7, the color filters of a red (R), a blue (B), a Gr(green in the red (R) row), and a Gb (green in the blue (B) row) arearranged in the Bayer array pattern. Filters of each color correspond totheir respective different one of the pixels. Thus, in the example ofFIG. 7, the light transmitted through each filter of Gb, B, R, and Gr ismainly incident upon their respective photodiodes of pixels differentfrom each other. However, as described above, the light is also incidentupon each neighboring pixels, thereby causing color mixing.

By arranging each color in this way, the color of neighboring pixelsvaries according to each color of the target pixel. Thus, the amount ofcolor mixing of each color varies according to each color of the targetpixel. As a result, the color mixing detection pixel 121 is provided ateach of R, B, Gr, and Gb.

In an example of FIG. 8, a color mixing detection pixel 121-1 detectsthe amount of color mixing for a pixel of color R. A color mixingdetection pixel 121-2 detects the amount of color mixing for a pixel ofcolor Gr. A color mixing detection pixel 121-3 detects the amount ofcolor mixing in a pixel of color Gb. A color mixing detection pixel121-4 detects the amount of color mixing in a pixel of color B.

The light is incident upon a target pixel from its neighboring pixels inany direction. In other words, a color mixing is caused by theneighboring pixels in any direction (for example, up, down, left, right,and oblique directions). Thus, each of the color mixing detection pixelsis positioned in spatially discrete locations so that the color mixingdetection pixels may be not contiguous with each other as shown in FIG.9.

The light shielding film blocks the light incident upon the target pixelfrom entering the color mixing detection pixel. Thus, the color mixing(entering of the light) in the direction from the color mixing detectionpixel to its neighboring pixels is basically not caused (or negligiblyminimal). For example, as shown in FIG. 10, if the color mixingdetection pixels are disposed in contiguous relation to each other, thenthe color mixing is generally not caused between the adjacent colormixing detection pixels. Therefore, there is a high possibility that theamount of color mixing which is detected in the color mixing detectionpixel having such arrangement will be not equivalent to the amount ofcolor mixing of the normal pixel on which a light is incident fromneighboring pixels in all directions. That is, in such an arrangement,there is a possibility that the color mixing detection pixel will notaccurately detect the amount of color mixing. Thus, the color mixingdetection pixels are disposed apart from each other so that they are notdisposed in contiguous relation to each other as shown in FIG. 9.

If the amount of color mixing in an oblique direction is sufficientlysmall, then a plurality of the color mixing detection pixels may bedisposed in contiguous relation to each other in the oblique direction,as an example shown in FIG. 11. Further, as long as the detection of theamount of color mixing will be not affected by any arrangement directionincluding the oblique direction, the plurality of color mixing detectionpixels can be arranged in contiguous relation to each other.

As described above, the amount of color mixing can be more accuratelydetected and calculated by providing the color mixing detection pixelwithin the effective pixel area. Also, the amount of color mixing can bemore accurately calculated by providing the color mixing detection pixelfor each color. Moreover, the amount of color mixing can be more easilycalculated by providing the light shielding layer at the color mixingdetection pixel. The light shielding layer can be implemented in an easyway such as by forming a wiring layer or by providing a metal layer inthe form of a photodiode. Furthermore, with this method, a proper lightshielding layer can be provided depending on the amount or angle of theincident light, or the like, thereby more effectively blocking thelight.

[Signal Correction]

The image signal (image sensor signal) obtained by the image sensor withcolor filter 103 as described above is corrected as shown in FIG. 12. Inthe clamping unit 105, the black level detected in the OPB area isremoved from both a pixel value of the normal pixel and a pixel value ofthe color mixing detection pixel 121. Subsequently, in the color mixingsubtraction unit 106, the pixel value (amount of color mixing) of thecolor mixing detection pixel 121 is subtracted from the pixel value ofthe normal pixel. This allows the pixel value of the normal pixel tobecome a proper pixel value corresponding to only a light incident uponthe target pixel. In contrast, there is no light incident upon the colormixing detection pixel 121, thus the pixel value of the color mixingdetection pixel 121 is not a proper pixel value equivalent to the pixelvalue of the normal pixel. As a result, the defect correction unit 107corrects the pixel value by regarding the color mixing detection pixel121 as a defective pixel.

In practice, there may be a case that the pixel value of the colormixing detection pixel is different from the actual amount of colormixing of the normal pixel. Thus, for example, as described below, it ispossible to provide a configuration that the amount of color mixing ofthe position of the normal pixel is estimated by using a plurality ofthe actual color mixing detection pixels and the value obtained by theestimation is subtracted from the normal pixel.

The method of detecting a black level in the OPB area and the method ofsubtracting the black level by the clamping unit 105 are similar tomethods in the related art.

[Color Mixing Subtraction Unit]

FIG. 13 is a block diagram illustrating a configuration example of thecolor mixing subtraction unit 106 of FIG. 1.

As shown in FIG. 13, the color mixing subtraction unit 106 includes acontrol portion 131, a storage portion 132, a color mixing detectionpixel specifying portion 133, a color mixing amount calculation portion134, and a subtraction portion 135.

The control portion 131 is configured to determine whether or not atarget pixel to be processed is the color mixing detection pixel 121.The control portion 131 knows beforehand about the position of the colormixing detection pixel 121. If the target pixel to be processed isdetermined to be the color mixing detection pixel 121, then the controlportion 131 supplies a pixel value of the target pixel to the storageportion 132, and causes the storage portion 132 to store the pixelvalue. On the other hand, if the target pixel to be processed is notdetermined to be the color mixing detection pixel 121, then the controlportion 131 causes the color mixing detection pixel specifying portion133 to specify the color mixing detection pixel 121 to be used tosubtract the amount of color mixing.

The storage portion 132 is configured to store the pixel value of thecolor mixing detection pixel supplied from the control portion 131. Thestorage portion 132 supplies the stored pixel value to the color mixingdetection pixel specifying portion 133 at a predetermined timing or inresponse to a request from the external.

The color mixing detection pixel specifying portion 133 is configured tospecify the color mixing detection pixel 121 to be used to subtract theamount of color mixing of the target pixel. The color mixing detectionpixel specifying portion 133 preferentially selects the color mixingdetection pixel 121 positioned in the closest possible proximity to thetarget pixel from around the target pixel as the color mixing detectionpixel 121 to be used to subtract the amount of color mixing. The colormixing detection pixel specifying portion 133 obtains a pixel value ofthe specified color mixing detection pixel 121 from the storage portion132, and supplies the obtained pixel value to the color mixing amountcalculation portion 134.

The color mixing amount calculation portion 134 is configured tocalculate the amount of color mixing of the target pixel using the pixelvalue of the color mixing detection pixel 121 specified by the colormixing detection pixel specifying portion 133. The color mixing amountcalculation portion 134 supplies the calculated amount of color mixingto the subtraction portion 135.

The subtraction portion 135 is configured to subtract the amount ofcolor mixing supplied by the color mixing amount calculation portion 134from the pixel value of the target pixel. The subtraction portion 135supplies the pixel value of the target pixel from which the amount ofcolor mixing is subtracted to the defect correction unit 107.

[Calculation of Amount of Color Mixing]

A method of calculating an amount of color mixing by the color mixingamount calculation portion 134 will be described below. The color mixingdetection pixel specifying portion 133 selects a plurality of itsneighboring color mixing detection pixels for a target pixel. The colormixing amount calculation portion 134 calculates the amount of colormixing of the target pixel using the plurality of the color mixingdetection pixels.

As an example shown in FIG. 14, the color mixing amount calculationportion 134 calculates an amount of color mixing of the target pixel(normal pixel) of blue color (B) using the amount of color mixingdetected in a color mixing detection pixel 141 and a color mixingdetection pixel 142 (both pixels are color mixing detection pixelscorresponding to blue color (B)). In addition, it is assumed that alight amount detected in the color mixing detection pixel 141 is theamount of color mixing A. It is assumed that a light amount detected inthe color mixing detection pixel 142 is the amount of color mixing B. Inthis case, the color mixing amount calculation portion 134 can obtainthe amount of color mixing A and the amount of color mixing B by addingweights according to a distance from the target pixel to the colormixing detection pixel 141 and a distance from the target pixel to thecolor mixing detection pixel 142.

As an example shown in FIG. 14, there are two normal pixels of bluecolor (B) between the color mixing detection pixel 141 and the colormixing detection pixel 142. These normal pixels divide a space betweenthe two color mixing detection pixels into three equal parts. If theblue color pixel (Blue1) 143 of the two pixels near the color mixingdetection pixel 141 having the amount of color mixing A is the targetpixel, then the amount of color mixing of the blue color pixel (colormixing component of Blue1) can be obtained as the following Equation(1).

Color mixing component of Blue1=(2×A)+(1×B)/(2+1)  (1)

Also, as the example shown in FIG. 14, if the blue color pixel (Blue2)144 near the color mixing detection pixel 142 having the amount of colormixing B is the target pixel, then the amount of color mixing of theblue color pixel (color mixing component of Blue2) can be obtained asthe following Equation (2).

Color mixing component of Blue2=(1×A)+(2×B)/(1+2)  (2)

As an example shown in FIG. 15, it is assumed that the amounts of colormixing of a blue color pixel 152 and a blue color pixel 153 in a frame150 are obtained. As shown in FIG. 15, the blue color pixel 152 and theblue color pixel 153 are both positioned between a color mixingdetection pixel 151 of blue color and a color mixing detection pixel 154of blue color. Thus, as shown in the graph of FIG. 15, the amounts ofcolor mixing of the blue color pixel 152 and the blue color pixel 153are both calculated by linear interpolation using the amount of colormixing A of the color mixing detection pixel 151 and the amount of colormixing B of the color mixing detection pixel 154.

Further, for example, a blue color pixel 155 and a blue color pixel 156are both positioned between the color mixing detection pixel 154 of bluecolor and a color mixing detection pixel 157 of blue color. Thus, asshown in the graph of FIG. 15, the amounts of color mixing of the bluecolor pixel 155 and the blue color pixel 156 are both calculated bylinear interpolation using the amount of color mixing B of the colormixing detection pixel 154 and the amount of color mixing C of the colormixing detection pixel 157.

The method of calculating the amount of color mixing is not limited tothose described above. For example, as an example shown in FIG. 16,there may be provided a method of dividing into each area and uniformlysubtracting the amount of color mixing in each area. In this method, asthe example shown in FIG. 16, the amount of color mixing of the nearestneighboring color mixing pixel is employed as the amount of color mixingof the concerned area to be processed. Thus, as shown in the graph ofFIG. 16, the amount of color mixing of a blue color pixel 162 in a frame160 is set to the amount of color mixing A of a color mixing detectionpixel 161 of blue color. In addition, the amounts of color mixing of ablue color pixel 171 and a blue color pixel 173 in a frame 170 are setto the amount of color mixing B of a color mixing detection pixel 172 ofblue color. The amount of color mixing of a blue color pixel 181 in aframe 180 is set to the amount of color mixing C of a color mixingdetection pixel 182 of blue color. This method allows the amount ofcolor mixing of the concerned area to be obtained easier than the methodof using the weight addition described above. However, since the amountof color mixing is generally less likely to be suddenly changed, themethod of using the weight addition described above can more accuratelyobtain the amount of color mixing.

Although there has been described a one-dimensional arrangement as anexample, the operations described above may be performed using atwo-dimensional arrangement. Specifically, the amount of color mixingcan be calculated using a color mixing detection pixel positioned nearerto the target pixel in the two-dimensional arrangement (in any directionsuch as up, down, left, right or oblique).

As an example shown in FIG. 17, color mixing detection pixels 185 to 187are color mixing detection pixels of blue color. The amounts of colormixing of other blue color pixels are calculated by adding weights ofthe amount of color mixing of two pixels positioned near to the targetpixel in the two-dimensional arrangement.

For example, in the two-dimensional arrangement, color mixing detectionpixels (two pixels) having a shorter distance to the target pixel fromwhich its amount of color mixing is calculated are assumed to be thecolor mixing detection pixels 185 and 186. In this case, the amount ofcolor mixing of the target pixel is calculated by adding weights to theamount of color mixing A of the color mixing detection pixel 185 and theamount of color mixing B of the color mixing detection pixel 186according to the distances between the respective color mixing detectionpixels and the target pixel.

The number of the color mixing detection pixel used to calculate theamount of color mixing is not particularly limited and can be suitablyselected. For example, the number of the color mixing detection pixelmay be three or more.

As described above, since the amount of color mixing varies depending onthe colors or surrounding structures (neighboring colors), only thecolor mixing detection pixel having the same color as the concerned areais used to calculate the amount of color mixing. For example, in orderto calculate the amount of color mixing of a blue color pixel, theamount of color mixing of the color mixing detection pixel of blue colornearer to the blue color pixel is used.

[Correction of Amount of Color Mixing]

As shown in FIG. 18, the subtraction portion 135 subtracts the amount ofcolor mixing 192 calculated as described above from a pixel value 191from which a black level is removed, thereby obtaining a pixel value 193which is a value from which the black level and the amount of colormixing are subtracted.

[Defect Correction]

The defect correction unit 107 corrects a color mixing detection pixelby regarding the color mixing detection pixel as a defective pixel.Since the color mixing detection pixel outputs only the amount of colormixing, the proper image may not be obtained without any furtherprocessing. Thus, the defect correction unit 107 regards the colormixing detection pixel as a defective pixel, and replaces the pixel witha signal value obtained from a normal pixel. The method of correctingthe defect is not limited to a particular method. As an example shown inFIG. 19, there may be provided a method (for example, linearinterpolation) of estimating from an output value (value aftersubtracting the color mixing) of each neighboring normal pixels havingsame color. In the example shown in FIG. 19, the pixel value A of thecolor mixing detection pixel of blue color is corrected and changed intothe pixel value 80 from two pixel values 100 and 80 of the neighboringblue color pixels.

The imaging apparatus 100 can more accurately correct color mixing bycorrecting the amount of color mixing and so on as described above.

[Procedure of Imaging Process]

Each of the processes performed by individual units of the imagingapparatus 100 will be described. Referring to the flowchart of FIG. 20,an exemplary procedure of imaging process performed by the imagingapparatus 100 upon capturing a subject will be described.

When the imaging process is started, in step S101, the image sensor withcolor filter 103 converts the incident light of each pixel intoelectrical signals and reads out each pixel signal. In step S102, theA/D converter 104 performs A/D conversion on the respective pixelsignals obtained in the step S101.

In step S103, the clamping unit 105 subtracts the black level detectedin the OPB area from the respective pixel values. In step S104, thecolor mixing subtraction unit 106 subtracts the amount of color mixingfrom the pixel values. In step S105, the defect correction unit 107corrects the pixel value of the defective pixel having a color mixingdetection pixel.

In step S106, the demosaic unit 108 performs a demosaic process andconverts RAW data into RGB data. In step S107, the linear matrix unit109 performs a color correction process depending on the characteristicsof an input device. In step S108, the gamma correction unit 110 performsa gamma correction process depending on the characteristics of an outputdevice.

In step S109, the luminance and chroma signal generation unit 111generates a luminance signal and a chrominance signal (Y, Cr, and Cbdata) from RGB data. In step S110, the interface (I/F) unit 112 outputsthe luminance and chrominance signals generated in step S109 to anexternal storage device or display device, and then the imaging processis finished.

[Procedure of Color Mixing Subtraction Process]

An exemplary procedure of the color mixing subtraction process performedat step S104 of FIG. 20 will be described with reference to theflowchart of FIG. 21.

When the color mixing subtraction process is started, in step S131, thecontrol portion 131 determines whether or not a target pixel to beprocessed is a color mixing detection pixel. If the target pixel isdetermined to be the color mixing detection pixel, then the controlportion 131 moves the process to step S132. In step S132, the storageportion 132 stores a pixel value of the color mixing detection pixel,and the process proceeds to step S137.

In step S131, if the target pixel is not determined to be the colormixing detection pixel, then the control portion 131 moves the processto step S133.

In step S133, the color mixing detection pixel specifying portion 133specifies the color mixing detection pixel to be used to calculate theamount of color mixing of the target pixel according to a predeterminedmethod. For example, the color mixing detection pixel specifying portion133 specifies the predetermined number of the color mixing detectionpixel nearer to the target pixel as the color mixing detection pixel tobe used to calculate the amount of color mixing of the target pixel. Instep S134, the color mixing detection pixel specifying portion 133obtains the pixel value of the color mixing detection pixel specified instep S133 from the storage portion 132.

In step S135, the color mixing amount calculation portion 134 calculatesthe amount of color mixing of the target pixel by using the pixel valueof the color mixing detection pixel obtained in step S134. In step S136,the subtraction portion 135 subtracts the amount of color mixingcalculated in step S135 from the pixel value of the target pixel (thepixel of interest) to be processed. When the subtraction process iscompleted, the subtraction portion 135 moves the process to step S137.

In step S137, the control portion 131 determines whether there is anyunprocessed pixel. When it is determined that there is a pixel on whichthe subtraction is not performed, the process returns to step S131 andthen repeats the subsequent steps. Furthermore, in step S137, if it isdetermined that all the amount of color mixing are subtracted from thenormal pixels, then the control portion 131 finishes the process andreturns it to steps of FIG. 20.

By performing the processes as described above, the imaging apparatus100 can correct color mixing more accurately. In particular, it ispossible to optimally correct the amount of color mixing depending onany imaging conditions such as a light amount, a color temperature oflight, an angle of incidence, a subject, and so on. Moreover, the colormixing detection pixel is arranged in an actual device, and thus it ispossible to correct color mixing more accurately and to prevent a falsecolor by error correction from being generated. In addition, althoughthe color mixing causes degradation of S/N ratio or colorreproducibility, it is possible to improve the color mixing and S/Nratio in accordance with embodiments of the present disclosure.

The resolution can be also enhanced by the improvement of color mixing.Although it has been described that the color mixing causes a bluroccurring when a photon or electron is moved between neighboring pixels,it is possible to correct this color mixing causing a blur. Thus, it ispossible to obtain the output having a high definition resolutionwithout a blur. Furthermore, the correction of color mixing may beapplied to a wide range of applications and may be not limited to theBayer array. Also, this technique is useful for improving the colormixing of many devices such as a clear bit type or a vertical spectralstructure.

Second Embodiment

[Configuration of Imaging Apparatus]

It is possible to perform the subtraction of black level and thecorrection of color mixing simultaneously. FIG. 22 is a diagramillustrating a configuration of the imaging apparatus according to anembodiment of the present disclosure. The imaging apparatus 200 shown inFIG. 22 is basically similar to the imaging apparatus 100 shown inFIG. 1. That is, the imaging apparatus 200 has a similar configurationto the imaging apparatus 100 and performs a similar process to theimaging apparatus 100.

The imaging apparatus 200 includes a color mixing and black levelsubtraction unit 205, instead of the clamping unit 105 and the colormixing subtraction unit 106 of the imaging apparatus 100.

The color mixing and black level subtraction unit 205 performs thesubtraction of the color mixing and black level simultaneously for thepixel data on which A/D conversion is performed. More specifically, thecolor mixing and black level subtraction unit 205 subtracts a pixelvalue of the color mixing detection pixel from a pixel value of thenormal pixel in the state before the black level is removed, as shown inFIG. 23. The color mixing detection pixel originally becomes a blacklevel because the color mixing detection pixel is light-shielded. Thecolor mixing from its neighboring pixels is added to the black level.The total value obtained from addition of the black level and colormixing is outputted from the image sensor. Thus, the only incident lightsignal desired to be obtained can be acquired by subtracting the totalvalue from a normal pixel.

In the first embodiment, the black level is detected by using OPB areaoutside an effective area. In accordance with the second embodiment, theblack level and the amount of color mixing are both detected in aplurality of the color mixing detection pixels disposed within a sensor.Therefore, it is possible to eliminate the need of OPB area inaccordance with the second embodiment. So, the image sensor with colorfilter having a smaller chip size is possible and the cost can bereduced.

As shown in FIG. 24, the black level containing a dark output (darkcurrent) is not necessarily uniform in the sensor due to manufacturingvariations. In this case, because respective black levels are obtainedfor each area as the color mixing, dark current shading can be correctedsimultaneously.

Similar to the first embodiment, the pixel value of the color mixingdetection pixel may be not necessarily completely consistent with theactual amount of color mixing of the normal pixel. In this case, in asimilar way as described in the first embodiment, a pixel value (totalvalue obtained from addition of the black level and the amount of colormixing) of a color mixing detection pixel corresponding to a position ofa normal pixel may be estimated using pixel values of a plurality of thecolor mixing detection pixels, and then the estimation value may besubtracted from the pixel value of the normal pixel.

[Procedure of Imaging Process]

A procedure example of the imaging process in the case as describedabove will be described with reference to the flowchart of FIG. 25. Asshown in the flowchart of FIG. 25, substantially similar processes tothe case described above with respect to the flowchart of FIG. 20 areperformed.

Specifically, each of the processes which will be performed at stepS201, step S202, and steps S204 to S209 of FIG. 25 are similar to therespective processes performed at step S101, step S102, and steps S105to S110 of FIG. 20.

As a difference between the processes of FIG. 20 and FIG. 25, a processof step S203 of FIG. 25 is performed instead of the processes of stepsS103 and S104 of FIG. 20. In step S203, the color mixing and black levelsubtraction unit 205 performs a color mixing and black level subtractionprocess.

[Procedure of Color Mixing and Black Level Subtraction Process]

Next, referring to the flowchart of FIG. 26, a procedure example of thecolor mixing and black level subtraction process which is performed atstep S203 of FIG. 25 will be described.

The procedure of the color mixing and black level subtraction process isbasically similar to the procedure of the color mixing subtractionprocess described above with reference to the flowchart of FIG. 21,except that the color mixing and black level subtraction processperforms the subtraction of black level as well as color mixing.Processes different from the color mixing subtraction process of FIG. 21will be described below.

In step S223, the color mixing and black level subtraction unit 205specifies a color mixing detection pixel to be used in calculating thecolor mixing and black level. Further, in step S225, the color mixingand black level subtraction unit 205 calculates a color mixing and blacklevel of the target pixel to be processed, using the pixel value of thecolor mixing detection pixel obtained in step S224.

In step S226, the color mixing and black level subtraction unit 205subtracts the color mixing and black level from the pixel value of thetarget pixel (the pixel of interest) to be processed.

Like the imaging apparatus 100, the imaging apparatus 200 can moreaccurately correct color mixing by performing each process as describedabove.

Third Embodiment Application Example 1

As a method of estimating the amount of color mixing, a method ofcalculating a color mixing ratio and then calculating the amount ofcolor mixing may be contemplated. For example, a case where the colormixing detection pixel and the pixel to be corrected may be differentfrom each other in brightness depending on a subject to be captured maybe contemplated. In this case, since the amount of color mixing variesdepending on light amount, the color mixing detection pixel and thepixel to be corrected may be largely different from each other in theamount of color mixing. For example, if the amount of color mixingobtained from a light part is subtracted from a signal value of a darkpart, then the overcorrection is caused (because the more light amountor signal becomes large, the more the amount of color mixing isincreased). In order to suppress such a phenomenon, the color mixingratio may be obtained earlier than the amount of color mixing.

FIG. 27 is a block diagram illustrating a configuration example of thecolor mixing subtraction unit 106 in the case as described above. Asshown in FIG. 27, the color mixing subtraction unit 106 has a similarconfiguration to that shown in FIG. 13, except that the color mixingsubtraction unit 106 includes a color mixing ratio calculation portion304 instead of the color mixing amount calculation portion 134 andincludes a multiplication portion 305 instead of the subtraction portion135.

The color mixing ratio calculation portion 304 calculates a color mixingratio which indicates a ratio of a color mixing component for the entirepixel value rather than the amount of color mixing of the target pixelto be processed. The multiplication portion 305 multiplies the pixelvalue of the target pixel to be processed, by the signal ratio ofincident light corresponding to the color mixing ratio.

In this case, the correction (subtraction) of color mixing is, forexample, performed as the example shown in FIG. 28. The difference isthat an output value of an adjacent pixel or neighboring pixel (i.e.,surrounding pixel) of a color mixing detection pixel is used foroperation. In the output of the clamping unit 105, it is assumed thateach pixel value of the target pixel (normal pixel) to be processednecessary to correct the color mixing, a color mixing detection pixel tobe used to correct the color mixing, and a surrounding pixel(neighboring pixel of a color mixing detection pixel) of the colormixing detection pixel has respective values, as follows:

Pixel value of normal pixel to correct color mixing: 50

Pixel value of color mixing detection pixel: 30

Pixel value of neighboring pixel of color mixing detection pixel: 100

The neighboring pixel of the color mixing detection pixel is assumed tobe positioned nearer to the color mixing detection pixel rather than thenormal pixel to correct color mixing.

It is estimated that the color mixing detection pixel has a pixel valueof “100”, from the fact that a neighboring pixel of the color mixingdetection pixel has the pixel value of “100” on the assumption that thecolor mixing detection pixel is not light-shielded. Specifically, it canbe found that the amount of color mixing is “30” and the incident lightsignal is “70” out of a total signal value of 100. In other words, thecolor mixing ratio is 30 percent (%) of the total signal value (incidentlight signal ratio is 70%). Therefore, the color mixing subtraction unit106 multiplies these respective pixel values by a value of 70% which isa signal ratio of the incident light corresponding to the color mixingratio.

Pixel value of normal pixel to correct color mixing: 50×0.7=35

Pixel value of color mixing detection pixel: 30×0.7=21

Pixel value of neighboring pixel of color mixing detection pixel:100×0.7=70

The defect correction unit 107 further performs defect correction of thecolor mixing detection pixel (replaced by neighboring pixel value and soon).

Output value of normal pixel to correct color mixing: 35

Color mixing detection pixel: 70

Neighboring pixel of color mixing detection pixel: 70

This enables a desired signal value without color mixing to be obtained.The estimation method described above with reference to FIGS. 14 to 17may be applied to the color mixing ratio in a similar way to the amountof color mixing as described above.

[Procedure of Color Mixing Subtraction Process]

Referring to the flowchart of FIG. 29, a procedure of the color mixingsubtraction process will be described below.

The procedure of the color mixing subtraction process is basicallysimilar to that of the color mixing subtraction process described abovewith reference to the flowchart of FIG. 21, except that the color mixingsubtraction process uses the color mixing ratio instead of the amount ofcolor mixing. Hereinafter, processes different from the color mixingsubtraction process of FIG. 21 will be described.

In step S304, the color mixing detection pixel specifying portion 133obtains the pixel value of the color mixing detection pixel specified instep S303. The color mixing detection pixel specifying portion 133 alsoobtains a pixel value of neighboring pixel of the color mixing detectionpixel specified in step S303.

In step S305, the color mixing ratio calculation portion 304 calculatesa color mixing ratio by using both a pixel value of the color mixingdetection pixel obtained in step S304 and a pixel value of neighboringpixel of the color mixing detection pixel.

In step S306, the multiplication portion 305 multiplies a pixel value ofthe target pixel (the pixel of interest) to be processed, by a signalratio of incident light corresponding to the color mixing ratiocalculated in step S305.

Like the imaging apparatus 100, the color mixing subtraction unit 106can more accurately subtract color mixing by performing each processdescribed above.

Application Example 2

As an example, if the surroundings of the color mixing detection pixelare saturated, then, in the method described above, there is apossibility that the proper amount of color mixing or color mixing ratiowill not be obtained. For example, the color mixing ratio is obtained bycalculating the ratio of the amount of color mixing to the total signalvalue containing both the incident light signal and the amount of colormixing. However, if the amount of color mixing is larger than saturationamount, then there is a possibility that total signal amount becomes apredetermined amount but the output of the shielded color mixingdetection pixel is increased or decreased depending on the light amount.If this value is applied to the other unsaturated pixel, then erroneouscolor mixing correction is likely to be caused.

As an example shown in FIG. 30, when the light amount of a pixel isunsaturated as shown in a left portion of FIG. 30, the ratio of thepixel value of the color mixing detection pixel to the pixel value ofthe neighboring pixel of the color mixing detection pixel iscorresponded to the color mixing ratio. In comparison, when the lightamount of a pixel is oversaturated as shown in a right portion of FIG.30, the ratio of the pixel value of the color mixing detection pixel tothe pixel value of neighboring pixel of the color mixing detection pixelis not corresponded to the color mixing ratio. That is, it could becontemplated that proper color mixing ratio becomes difficult to beobtained.

Therefore, when the neighboring pixel of the color mixing detectionpixel is saturated, the color mixing ratio (amount of color mixing) maybe obtained using a value of unsaturated neighboring pixel of the colormixing detection pixel rather than using a value of the concerned colormixing detection pixel.

FIG. 31 illustrates more specific example. In the example shown in FIG.31, surrounding pixels of the color mixing detection pixel B aresaturated. In FIG. 31, when a target pixel 331 is to be corrected, amethod of blending the amount of color mixing or color mixing ratio ofthe color mixing detection pixels B and C depending on their distanceswill be contemplated. However, since the surrounding pixels of the colormixing detection pixel B are saturated, there is a high possibility thatthe accurate amount of color mixing or color mixing ratio as describedabove will not be obtained. Thus, in this case, the color mixingdetection pixels A and C may be used without using the color mixingdetection pixel B, thereby preventing erroneous correction from beingcaused.

[Procedure of Color Mixing Detection Pixel Specifying Process]

Referring to the flowchart of FIG. 32, a procedure of the color mixingdetection pixel specifying process will be described. This color mixingdetection pixel specifying process, for example, is a process performedat step S133 of FIG. 21.

When the color mixing detection pixel specifying process is started, instep S331, the color mixing detection pixel specifying portion 133specifies a color mixing detection pixel to be used to calculate colormixing. In step S332, the color mixing detection pixel specifyingportion 133 obtains a predetermined number (one or more) of pixel valueof each neighboring pixel of the color mixing detection pixel specifiedin step S331.

In step S333, the color mixing detection pixel specifying portion 133determines whether one or more pixel values of the neighboring pixel aresaturated. If it is determined that one or more pixel values of theneighboring pixel are saturated, then the process proceeds to step S334.

In step S334, the color mixing detection pixel specifying portion 133updates the color mixing detection pixel used to calculate color mixinginto other color mixing detection pixel. That is, the color mixingdetection pixel can be avoided when its neighboring pixel is saturated.If the process of step S334 is finished, then the color mixing detectionpixel specifying portion 133 moves the process to step S335.Furthermore, in step S333, if it is determined that any one of pixelvalues of each neighboring pixel is not saturated, then the color mixingdetection pixel specifying portion 133 moves the process to step S335.

In step S335, the color mixing detection pixel specifying portion 133determines whether or not there is any unprocessed color mixingdetection pixel used to calculate the amount of color mixing. In stepS331, if it is determined that there is an unprocessed pixel in whichpixel values of each neighboring pixel are not checked among thespecified color mixing detection pixel used to calculate the amount ofcolor mixing, then the color mixing detection pixel specifying portion133 returns the process to step S332 and repeats the subsequent steps.

In step S335, if it is determined that the neighboring pixels of thecolor mixing detection pixel, which is specified in FIG. 331, used tocalculate the amount of color mixing are all checked, the color mixingdetection pixel specifying portion 133 moves the process to step S336.

In step S336, the color mixing detection pixel specifying portion 133decides a candidate of the color mixing detection pixel which isnarrowed down by the process described above as the color mixingdetection pixel to be used to calculate the amount of color mixing, andthen color mixing detection pixel specifying process is finished.

The color mixing subtraction unit 106 can more accurately obtain theamount of color mixing (color mixing ratio) by properly selecting thecolor mixing detection pixel to be used to calculate the amount of colormixing depending on whether or not a pixel value of its neighboringpixel is saturated.

An image sensor may contain any defect such as a white point (outputrises) or black point (output falls) due to a number of factors such asdefects in a Si or transfer failure. Similarly, the color mixingdetection pixel also may contain such defects. Since such defects causean erroneous amount of color mixing, it is necessary to prevent suchdefects. Thus, the determination of whether the color mixing detectionpixel is a defective pixel may be contemplated. If it is determined thatthe color mixing detection pixel is a defective pixel, then it may becontemplated that the pixel will be not used. As an example shown inFIG. 31, if the color mixing detection pixel B is a defective pixel, theamount of color mixing and color mixing ratio may be obtained using theother color mixing detection pixel B or C.

The determination of whether a color mixing detection pixel is adefective pixel can be performed by a method carried out generally whenthe defect is corrected. For example, a method of determining whether ornot there is a jump value among a plurality of values of the colormixing detection pixel may be considered. More specifically, forexample, when the pixel value of the color mixing detection pixel Bpositioned between the color mixing detection pixels A and C is greatlydifferent (e.g., more than twice) from the pixel values of the colormixing detection pixels A and C, the color mixing detection pixel B maybe regarded as a defective pixel, thereby prohibiting the color mixingdetection pixel B from being used in calculating the amount of colormixing (color mixing ratio).

As an approach for the case where the pixel value of neighboring pixelof the target pixel is determined to be saturated or the case where theconcerned color mixing detection pixel is determined to be a defectivepixel, any method other than those described above may be employed.Although the method that the color mixing detection pixel used tocalculate the amount of color mixing is changed (updated) from theconcerned color mixing detection pixel into other color mixing detectionpixel has been described above, any method other than those describedabove may be employed as an approach to avoid such circumstances. Forexample, the concerned color mixing detection pixel may be prohibitedfrom being used to calculate the amount of color mixing.

For example, it is assumed that a plurality of the color mixingdetection pixels are used to calculate the amount of color mixing. Inany one of the plurality of color mixing detection pixels, if the lightamount of its neighboring pixel is saturated or if it is determined thecolor mixing detection pixel is a defective pixel as described above,then the only concerned color mixing detection pixel may be prohibitedfrom being used and then other color mixing detection pixels may beprevented from being newly used. That is, in this case, the number ofthe color mixing detection pixel used to calculate the amount of colormixing is reduced.

Application Example 3

Like a pixel 351 shown in FIG. 33, since color mixing is generally notcaused from a light-shielded pixel, the amount of color mixing of aneighboring pixel of the color mixing detection pixel beinglight-shielded is less than that of other pixels. Thus, if the colormixing amount subtraction is performed on the neighboring pixel in asimilar way to other pixel, then there is a possibility that anovercorrection will be caused.

Thus, for neighboring pixels (up, down, left, right, and oblique) of thecolor mixing detection pixel, the color mixing correction amount may bereduced (for example, the reduced amount is 0.8 times the amount ofcolor mixing or color mixing ratio obtained from the color mixingdetection pixel) or they may be regarded as defective pixels and thus asignal value may be reconstructed by defect correction.

[Procedure of Color Mixing Subtraction Process]

With reference to the flowchart of FIG. 34, a procedure of the colormixing subtraction process which is performed when a color mixingcorrection amount of each neighboring pixel of the color mixingdetection pixel is reduced will be described.

In this case, each of the processes performed at step S351 to S355,S358, and S359 of FIG. 34 are similar to the respective processesperformed at step S131 to S137 of FIG. 21.

In the example shown in FIG. 34, steps S356 and S357 are additionallyperformed. Specifically, in step S356, the color mixing amountcalculation portion 134 determines whether or not the target pixel to beprocessed is a pixel adjacent to the color mixing detection pixel. If itis determined that the target pixel is a pixel adjacent to the colormixing detection pixel (that is, the adjacent pixel is located at aposition where a color mixing is occurred from the color mixingdetection pixel which is a normal pixel), the color mixing amountcalculation portion 134 moves the process to step S357. In step S357,the color mixing amount calculation portion 134 further corrects (forexample, multiplies a predetermined value (e.g., 0.8 times)) the amountof color mixing calculated in step S355.

If the process in step S357 is completed, the color mixing amountcalculation portion 134 moves the process to step S358. Also, in stepS356, if it is determined that the target pixel to be processed is not apixel adjacent to the color mixing detection pixel, the color mixingamount calculation portion 134 moves the process to step S358.

In accordance with the process described above, the color mixingsubtraction unit 106 can obtain the amount of color mixing (color mixingratio) more accurately and can correct color mixing more accurately.

The method of correcting defects may be performed in a similar manner asthose for the color mixing detection pixel.

Application Example 4

As described above, it has been described that a color mixing detectionpixel is provided for each color of color filters and all colors arecorrected. But there is the possibility that the number of the defectivepixel to be corrected will be increased as the number of the colormixing detection pixel becomes large.

Since the defect correction is performed by estimating from a value of aneighboring normal pixel, if such estimation value is erroneous, thenthere is a possibility that a false color or resolution degradation willbe occurred. Thus, in order to prevent the estimation value from beingerroneous as much as possible and to improve an image quality by thecolor mixing correction, it is considered that the color mixingdetection pixel is provided only at a particular color and thecorrection of the amount of color mixing is performed for the particularcolor.

For example, in a sensor under development, when it is determined thatthe amount of color mixing for a Red color pixel is larger than othercolor pixels, it is possible that a color mixing detection pixel isprovided only at the Red color pixel and the correction of the amount ofcolor mixing is performed for the Red color pixel. Thus, a color mixingdetection pixel may be not provided at Green and Blue color pixels and adefect correction also may be performed only for the color mixingdetection pixel of Red color.

Fourth Embodiment

[Vertical Spectral Structure]

Embodiments of the present disclosure can correct the amount of colormixing by providing a light-shielded pixel and they can be applied toany pixel structure. For example, embodiments of the present disclosurecan be applied to an image sensor without color filter. For example, asthe method described in Japanese Patent Laid-open No. 2011-29453, thereis provided the vertical spectral structure in which photodiodes arearranged with three stages in a vertical direction within a same pixeland color signals are obtained from a plurality of the same pixel. Inpixels of this vertical spectral structure, each color may be identifiedonly with each photodiode. There is also provided a method of obtainingcolor signals using an organic photoelectric conversion film.Embodiments of the present disclosure can be also applied to an imagesensor having a pixel of the vertical spectral structure in the similarway to the image sensor using the color filter described above.

A case of using the image sensor of the vertical spectral structure willbe described below.

[Imaging Apparatus]

FIG. 35 is a block diagram illustrating a configuration example of theimaging apparatus in the case of using the image sensor of the verticalspectral structure. The imaging apparatus 400 shown in FIG. 35 isbasically similar to the imaging apparatus 100 shown in FIG. 1.Specifically, the imaging apparatus 400 has similar configuration to theimaging apparatus 100 and performs similar processes to the imagingapparatus 100. The difference is that the imaging apparatus 400 includesan image sensor without color filter 403 instead of the image sensorwith color filter 103.

The image sensor 403 is a surface irradiation type and a solid stateimage sensor capable of the vertical spectroscopy, as a cross-sectionalview shown in FIG. 36. This vertical spectral structure, for example, isa structure as described in Japanese Patent Laid-open No. 2011-29453. Inthis structure, three photodiodes (P-N junction) are stacked in avertical direction. The color signal having three colors can be obtainedfrom a single pixel by photoelectrically converting Blue in top stage,Green in middle stage, and Red in bottom stage.

For example, in FIG. 36, a surface type photodiode (PD) 36 is formed ina region at a depth of approximately 0.5 micrometers (μm) from a lightincident surface of a semiconductor substrate 14 to generate signalcharge by the blue color (B) of light. A first buried type photodiode(PD) 23 is formed in a region at a depth of approximately 0.5 to 1.5micrometers (μm) from a light incident surface of the semiconductorsubstrate 14 to generate signal charge by the green color (G) of light.A second buried type photodiode (PD) 57 is formed in a region at a depthof approximately 1.5 to 3 micrometers (μm) from a light incident surfaceof the semiconductor substrate 14 to generate a signal charge by the redcolor (R) of light for the case where entire thickness of thesemiconductor substrate 14 is, for example, 3 micrometers (μm). Thesecond buried type photodiode (PD) 57 may be extended in a depthdirection of the substrate for the case where entire thickness of thesemiconductor substrate 14 is thicker than 3 micrometers (μm).

Thus, the image sensor 403 capable of the vertical spectroscopy may notbe provided with a color filter layer at the light illumination portionof the semiconductor substrate 14. Within a single pixel, because allthe RGB lights can be photoelectrically converted, the utilizationefficiency of light for single pixel is three times higher than a pixelon which spectroscopy is performed using a color filter in the relatedart, thereby improving the sensitivity.

If pixels of the image sensor 403 have such vertical spectral structure,as shown in FIG. 37, a color mixing detection pixel is provided in thesimilar way to the methods of embodiments described above. However, inthe case of the vertical spectral structure, the entire RGB light in asingle pixel can be photoelectrically converted as described above.Thus, in also the case of the color mixing detection pixel, the colormixing for each color of RGB can be detected in a single pixel.

More specifically, as shown in FIG. 38, color mixing is occurred withina Si even with the vertical spectral structure. The output of colormixing detection pixel (middle portion of FIG. 38) which islight-shielded by a wiring layer becomes only a bulk color mixing fromneighboring pixels together with R, G, and B. This color mixing iscorrected by the same method as those of embodiments described above.The difference from the methods described above is that the color mixingof a plurality of pixels (for example, R, G, B) can be discriminatedfrom each other in a single pixel (an example of the read-out structureis described in Japanese Patent Laid-open No. 2011-29453).

In the imaging apparatus 400 shown in FIG. 35, since the image sensor403 has the vertical spectral structure and data of each color isobtained from each pixel, it is possible to eliminate the demosaic unit108. That is, the output of the defect correction unit 107 is directlysupplied to the linear matrix unit 109.

[Procedure of Imaging Process]

A procedure of an imaging process will be described with reference tothe flowchart of FIG. 39. This imaging process is basically performed ina similar manner as that of FIG. 20.

However, in step S401 of FIG. 39, pixel signals of a plurality of colorsare read out from a single pixel. Thus, in this case, a demosaic processcorresponding to step S106 is omitted.

This enables the imaging apparatus 400 to more accurately correct colormixing as those of the imaging apparatus 100.

Moreover, for example, it is possible to provide a configuration that asingle photodiode is provided for Green color and photodiodes having thevertical spectral structure are provided for Red and Blue colors. Inthis case, a demosaic process is necessary.

Fifth Embodiment

[Imaging Apparatus]

Even in the case where the image sensor without color filter 403 is usedas described in the fourth embodiment, the black level and the amount ofcolor mixing may be corrected simultaneously as described in the secondembodiment.

FIG. 40 is a block diagram illustrating a configuration example of theimaging apparatus in the case of using the image sensor without colorfilter. In FIG. 40, an imaging apparatus 500 has a basically similarconfiguration to that of the imaging apparatus 400 in FIG. 35. However,the imaging apparatus 500 includes a color mixing and black levelsubtraction unit 205 instead of the clamping unit 105 and the colormixing subtraction unit 106, as the imaging apparatus 200 shown in FIG.22.

More specifically, the imaging apparatus 500 corrects the black leveland the amount of color mixing simultaneously, as the imaging apparatus200. In comparison with the imaging apparatus 200, the imaging apparatus500 includes the image sensor 403 instead of the image sensor with colorfilter 103. Also, the demosaic unit 108 is omitted.

[Procedure of Imaging Process]

A procedure of the imaging process of the case described above will bedescribed with reference to the flowchart of FIG. 41. This imagingprocess is performed in a basically similar manner to that of the FIG.25.

However, in step S501 of FIG. 41, pixel signals of a plurality of colorsare read out from a single pixel. Thus, in this case, a demosaic processcorresponding to step S205 is omitted.

This enables the imaging apparatus 500 to more accurately correct colormixing as those of the imaging apparatus 200.

Sixth Embodiment

[Imaging Apparatus]

The imaging apparatus described above may be configured as a part ofother apparatus. For example, the imaging apparatus described above maybe configured as a part of the imaging apparatus shown in FIG. 42.

FIG. 42 is a block diagram illustrating a configuration example of animaging apparatus according to an embodiment of the present disclosure.

As shown in FIG. 42, an imaging apparatus 600 includes a lens unit 611,a CMOS sensor 612, an analog-to-digital (A/D) converter 613, anoperation unit 614, a control unit 615, an image processing unit 616, adisplay unit 617, a codec processing unit 618, and a storage unit 619.

The lens unit 611 adjusts a focal length to a subject, condenses a lightfrom a position in focus, and supplies it to the CMOS sensor 612.

The CMOS sensor 612 is a solid-state image sensor having theconfiguration described above and is provided with a color mixingdetection pixel in an effective pixel area.

The A/D converter 613 converts a voltage signal for each pixel suppliedfrom the CMOS sensor 612 at a predetermined timing into a digital imagesignal (hereinafter, appropriately referred to as “image signal”). TheA/D converter 613 also supplies the image signal to the image processingunit 616 sequentially at a predetermined timing.

The operation unit 614 may configured to include a Jog Dial (registeredtrademark), a key, a button, or a touch panel. The operation unit 614receives a user's operation input and supplies a signal corresponding tothe user's operation input to the control unit 615.

The control unit 615 controls the lens unit 611, the CMOS sensor 612,the A/D converter 613, the image processing unit 616, the display unit617, the codec processing unit 618, and the storage unit 619, based onthe signal corresponding to the user's operation input inputted to theoperation unit 614.

The image processing unit 616 performs a variety of processes such asthe color mixing correction described above, black level correction,white balance adjustment, demosaic processing, matrix processing, gammacorrection, YC conversion, and so on for the image signal supplied fromthe A/D converter 613. The image processing unit 616 supplies the imagesignal on which image processing is performed to both the display unit617 and the codec processing unit 618.

The display unit 617 may be configured to include a liquid crystaldisplay. The display unit 617 displays an image of a subject based onthe image signal from the image processing unit 616.

The codec processing unit 618 performs a predetermined coding process onthe image signal from the image processing unit 616 and supplies animage data obtained by the coding process to the storage unit 619.

The storage unit 619 stores the image data supplied from the codecprocessing unit 618. The image data stored in the storage unit 619 issupplied to the display unit 617 by reading out to the image processingunit 616 as necessary. The display unit 617 displays an imagecorresponding to the image data.

The imaging apparatus which includes the solid-state image sensor or theimage processing unit according to the embodiment of the presentdisclosure is not limited the configurations described above and otherconfigurations may be employed.

As has been described, the respective apparatus may be configured toinclude other configurations than those described above. The apparatusmay be configured as a single apparatus or as a system including aplurality of apparatus.

Seventh Embodiment

[Personal Computer]

The series of processes described above may be performed by hardware,software, or a combination of both. In this case, the series ofprocesses may be performed in a personal computer shown in FIG. 43.

In FIG. 43, a central processing unit (CPU) 701 of the personal computer700 performs a variety of processes according to a program stored in aread only memory (ROM) 702. The CPU 701 also performs a variety ofprocesses according to a program loaded from a storage unit 713 to arandom access memory (RAM) 703. For example, data which is necessary forthe CPU 701 to execute a variety of processes is also appropriatelystored in the RAM 703.

The CPU 701, the ROM 702, and the RAM 703 are connected to each othervia a bus 704. An input/output interface 710 is also connected to thebus 704.

The input/output interface 710 is connected to an input unit 711 such asa keyboard and a mouse. The input/output interface 710 is also connectedto an output unit 712. The output unit 712 may includes a speaker and adisplay such as a cathode ray tube (CRT) display or a liquid crystaldisplay (LCD). The input/output interface 710 is also connected to thestorage unit 713. The storage unit 713 may include a hard disk or asolid state drive (SSD) such as a flash memory. The input/outputinterface 710 is connected to a communication unit 714. Thecommunication unit 714 may include a modem or an interface such as awire or wireless local area networks (LANs). The communication unit 714performs a communication process via a network including the Internet.

The input/output interface 710 is also connected to a drive 715 asnecessary. Furthermore, a removable media 721 such as a magnetic disk,an optical disk, a magneto-optical disk, or a semiconductor memory isappropriately attached to the drive 715. A computer program which isread-out from the removable media 721 through the drive 715 is installedinto the storage unit 713 as necessary.

When the series of processes described above are performed by software,the programs constituting the software are installed from a network or arecording medium.

This recording medium may be configured to include the removable media721 in which the programs distributed to deliver to a user are storedindependently of the apparatus, as shown in FIG. 43. Examples of theremovable media 721 include a magnetic disk (including a flexible disk)or an optical disk (including a CD-ROM or DVD). Further, examples of theremovable media 721 include a magneto-optical disk (including MD(Mini-Disc)) or a semiconductor memory. The recording medium may beconfigured as the ROM 702 in which programs distributed to a user in astate pre-incorporated in the apparatus as well as the removable media721 are stored or may be configured as a hard disk included in thestorage unit 713.

Further, the programs executed by a computer may include not onlyprocesses performed in a time series according to the proceduresdescribed herein but also processes performed in parallel or at anecessary suitable timing such as when a call or routine is performed.

Moreover, in the present specification, the steps describing theprograms stored in the recording medium may include not only processesperformed in a time series according to the procedures described herein,but also processes performed in parallel or separately rather thannecessarily performed in the time series.

Also, in the present specification, the system may be an entire assemblyconfigured to include a plurality of devices (apparatus).

It should be appreciated that the configuration including a singleapparatus (or processing unit) as described herein may be configured toinclude a plurality of apparatus (or processing units). In contrast, theconfiguration including a plurality of apparatus (or processing units)as described herein may be configured to include a single apparatus (orprocessing unit). Also, configurations other than those described abovemay be added to the configuration of each apparatus (or processingunit). Further, a part of a configuration of any one apparatus (orprocessing unit) may be included in a configuration of other apparatus(or other processing unit) as long as the configuration or operation ofthe entire system will be substantially identical to each other. Exampleembodiments of the present disclosure should not be construed as limitedto example embodiments of the present disclosure set forth herein. Itshould be understood that various changes, substitutions and alterationsmay be made herein without departing from the scope of the presentdisclosure.

Additionally, the present technology may also be configured as below.

(1) An image sensor including:

a normal pixel group composed of a plurality of normal pixels, each ofthe normal pixels having a photoelectric conversion device forphotoelectrically converting an incident light; and

a detection pixel configured to detect a light incident from aneighboring pixel by the photoelectric conversion device within aneffective pixel area of the normal pixel group.

(2) The image sensor according to (1), wherein the detection pixelfurther includes a light shielding film configured to shield an incidentlight incident upon the detection pixel from outside.(3) The image sensor according to (2), wherein the light shielding filmis formed by a wiring layer.(4) The image sensor according to (3), wherein the light shielding filmis formed by a plurality of wiring layers.(5) The image sensor according to (4), wherein each of the wiring layershas a gap formed thereon at different positions from each other.(6) The image sensor according to (4) or (5), wherein each of the wiringlayers is arranged depending on an incident angle of an incident light.(7) The image sensor according to any of (2) to (6), wherein the lightshielding film is formed by a metal disposed on the photoelectricconversion device.(8) The image sensor according to any of (1) to (7), wherein the imagesensor includes a plurality of the detection pixels.(9) The image sensor according to (8), further including:

a filter configured to transmit an incident light of a predeterminedwavelength,

wherein a result obtained by detecting a light incident from theneighboring pixel by the detection pixel is used to correct a pixelvalue of a normal pixel provided with a filter configured to transmit anincident light having the same wavelength as a filter provided at thedetection pixel.

(10) The image sensor according to (8) or (9), wherein the detectionpixels are provided in positions that are not contiguous with eachother.(11) An imaging apparatus including:

an image sensor which includes

-   -   a normal pixel group composed of a plurality of normal pixels,        each of the normal pixels having a photoelectric conversion        device for photoelectrically converting an incident light, and    -   a detection pixel configured to detect a light incident from a        neighboring pixel by the photoelectric conversion device within        an effective pixel area of the normal pixel group; and

a subtraction unit configured to subtract a light amount of a lightincident from a neighboring pixel of the normal pixel from a pixel valueof the normal pixel by using a light amount of a light detected by thedetection pixel of the image sensor.

(12) The imaging apparatus according to (11), wherein the subtractionunit includes

a selection unit configured to select a detection pixel to be used insubtracting the light amount,

a light amount calculation unit configured to calculate the light amountincluded in a pixel value of a normal pixel to be processed using apixel value of the detection pixel selected by the selection unit, and

a light amount subtraction unit configured to subtract the light amountcalculated by the light amount calculation unit from a pixel value of anormal pixel to be processed.

(13) The imaging apparatus according to (12),

wherein the selection unit selects a plurality of detection pixels, and

wherein the light amount calculation unit calculates the light amount byadding a weight to each pixel value of the plurality of detection pixelsdepending on a positional relationship between the plurality ofdetection pixels selected by the selection unit and a normal pixel to beprocessed.

(14) The imaging apparatus according to (12) or (13), wherein the lightamount calculation unit changes the detection pixel used to calculatethe light amount to another detection pixel or prohibits the detectionpixel from being used, when a pixel value of a neighboring pixel of thedetection pixel selected by the selection unit is saturated.(15) The imaging apparatus according to any of (12) to (14), wherein thelight amount calculation unit changes the detection pixel used tocalculate the light amount to another detection pixel or prohibits thedetection pixel from being used, when the detection pixel selected bythe selection unit is a defective pixel.(16) The imaging apparatus according to any of (12) to (15), wherein thelight amount calculation unit further corrects the calculated lightamount to reduce the light amount, when a normal pixel to be processedis adjacent to a detection pixel.(17) The imaging apparatus according to any of (11) to (16), wherein thesubtraction unit subtracts a black level as well as the light amountfrom the pixel value of the normal pixel.(18) The imaging apparatus according to any of (11) to (17), wherein thesubtraction unit includes

a selection unit configured to select a detection pixel to be used insubtracting the light amount,

a ratio calculation unit configured to calculate a ratio of the lightamount included in a pixel value of a normal pixel to be processed usinga pixel value of the detection pixel selected by the selection unit, and

a multiplication unit configured to multiply a pixel value of a normalpixel to be processed by a ratio of an incident light inputted to thenormal pixel to be processed from outside, the ratio of the incidentlight being corresponded to the ratio of the light amount calculated bythe ratio calculation unit.

(19) The imaging apparatus according to any of (11) to (18), wherein thenormal pixel and the detection pixel of the image sensor have a verticalspectral structure.(20) An imaging method of an imaging apparatus having an image sensorincluding

a normal pixel group composed of a plurality of normal pixels, each ofthe normal pixels having a photoelectric conversion device forphotoelectrically converting an incident light; and

a detection pixel configured to detect a light incident from aneighboring pixel by the photoelectric conversion device within aneffective pixel area of the normal pixel group,

the imaging method including

subtracting, at a subtraction unit, a light amount of a light incidentfrom a neighboring pixel of the normal pixel from a pixel value of thenormal pixel using a light amount of a light detected by the detectionpixel of the image sensor.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2011-168946 filed in theJapan Patent Office on Aug. 2, 2011, the entire content of which ishereby incorporated by reference.

1. An image sensor comprising: a normal pixel group composed of aplurality of normal pixels, each of the normal pixels having aphotoelectric conversion device for photoelectrically converting anincident light; and a detection pixel configured to detect a lightincident from a neighboring pixel by the photoelectric conversion devicewithin an effective pixel area of the normal pixel group.
 2. The imagesensor according to claim 1, wherein the detection pixel furtherincludes a light shielding film configured to shield an incident lightincident upon the detection pixel from outside.
 3. The image sensoraccording to claim 2, wherein the light shielding film is formed by awiring layer.
 4. The image sensor according to claim 3, wherein thelight shielding film is formed by a plurality of wiring layers.
 5. Theimage sensor according to claim 4, wherein each of the wiring layers hasa gap formed thereon at different positions from each other.
 6. Theimage sensor according to claim 4, wherein each of the wiring layers isarranged depending on an incident angle of an incident light.
 7. Theimage sensor according to claim 2, wherein the light shielding film isformed by a metal disposed on the photoelectric conversion device. 8.The image sensor according to claim 1, wherein the image sensor includesa plurality of the detection pixels.
 9. The image sensor according toclaim 8, further comprising: a filter configured to transmit an incidentlight of a predetermined wavelength, wherein a result obtained bydetecting a light incident from the neighboring pixel by the detectionpixel is used to correct a pixel value of a normal pixel provided with afilter configured to transmit an incident light having the samewavelength as a filter provided at the detection pixel.
 10. The imagesensor according to claim 8, wherein the detection pixels are providedin positions that are not contiguous with each other.
 11. An imagingapparatus comprising: an image sensor which includes a normal pixelgroup composed of a plurality of normal pixels, each of the normalpixels having a photoelectric conversion device for photoelectricallyconverting an incident light, and a detection pixel configured to detecta light incident from a neighboring pixel by the photoelectricconversion device within an effective pixel area of the normal pixelgroup; and a subtraction unit configured to subtract a light amount of alight incident from a neighboring pixel of the normal pixel from a pixelvalue of the normal pixel by using a light amount of a light detected bythe detection pixel of the image sensor.
 12. The imaging apparatusaccording to claim 11, wherein the subtraction unit includes a selectionunit configured to select a detection pixel to be used in subtractingthe light amount, a light amount calculation unit configured tocalculate the light amount included in a pixel value of a normal pixelto be processed using a pixel value of the detection pixel selected bythe selection unit, and a light amount subtraction unit configured tosubtract the light amount calculated by the light amount calculationunit from a pixel value of a normal pixel to be processed.
 13. Theimaging apparatus according to claim 12, wherein the selection unitselects a plurality of detection pixels, and wherein the light amountcalculation unit calculates the light amount by adding a weight to eachpixel value of the plurality of detection pixels depending on apositional relationship between the plurality of detection pixelsselected by the selection unit and a normal pixel to be processed. 14.The imaging apparatus according to claim 12, wherein the light amountcalculation unit changes the detection pixel used to calculate the lightamount to another detection pixel or prohibits the detection pixel frombeing used, when a pixel value of a neighboring pixel of the detectionpixel selected by the selection unit is saturated.
 15. The imagingapparatus according to claim 12, wherein the light amount calculationunit changes the detection pixel used to calculate the light amount toanother detection pixel or prohibits the detection pixel from beingused, when the detection pixel selected by the selection unit is adefective pixel.
 16. The imaging apparatus according to claim 12,wherein the light amount calculation unit further corrects thecalculated light amount to reduce the light amount, when a normal pixelto be processed is adjacent to a detection pixel.
 17. The imagingapparatus according to claim 11, wherein the subtraction unit subtractsa black level as well as the light amount from the pixel value of thenormal pixel.
 18. The imaging apparatus according to claim 11, whereinthe subtraction unit includes a selection unit configured to select adetection pixel to be used in subtracting the light amount, a ratiocalculation unit configured to calculate a ratio of the light amountincluded in a pixel value of a normal pixel to be processed using apixel value of the detection pixel selected by the selection unit, and amultiplication unit configured to multiply a pixel value of a normalpixel to be processed by a ratio of an incident light inputted to thenormal pixel to be processed from outside, the ratio of the incidentlight being corresponded to the ratio of the light amount calculated bythe ratio calculation unit.
 19. The imaging apparatus according to claim11, wherein the normal pixel and the detection pixel of the image sensorhave a vertical spectral structure.
 20. An imaging method of an imagingapparatus having an image sensor including a normal pixel group composedof a plurality of normal pixels, each of the normal pixels having aphotoelectric conversion device for photoelectrically converting anincident light; and a detection pixel configured to detect a lightincident from a neighboring pixel by the photoelectric conversion devicewithin an effective pixel area of the normal pixel group, the imagingmethod comprising subtracting, at a subtraction unit, a light amount ofa light incident from a neighboring pixel of the normal pixel from apixel value of the normal pixel using a light amount of a light detectedby the detection pixel of the image sensor.